JP4506057B2

JP4506057B2 - Cold crucible melting and casting equipment

Info

Publication number: JP4506057B2
Application number: JP2001265168A
Authority: JP
Inventors: 英顕只野
Original assignee: Fuji Electric Systems Co Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 2001-06-15
Filing date: 2001-09-03
Publication date: 2010-07-21
Anticipated expiration: 2021-09-03
Also published as: JP2003065679A

Description

【０００１】
【発明の属する技術分野】
この発明は、高周波電源を用いてコイルを励磁し、水冷金属るつぼ中の金属材料を誘導加熱溶解して、溶湯を鋳型に鋳造するコールドクルーシブル溶解鋳造装置に関する。
【０００２】
【従来の技術】
コールドクルーシブル溶解装置は水冷された金属製るつぼの周囲に高周波誘導コイルが巻かれた装置である。水冷金属るつぼの内部に金属を入れ、コイルに高周波電流を流すと金属には渦電流が誘起され、金属は加熱され溶解する。この方法で溶解した金属は、水冷金属るつぼからの不純物の混入がないので、高純度の溶湯ができる。またこの溶湯を鋳型に鋳造することにより高純度鋳造製品の生産が可能で例えばチタニウム等の活性金属、高融点金属（クロム、ニオブ、モリブデン）、シリコン等の溶解に適している。また水冷金属るつぼに作用する電磁力が強いので溶湯は電磁攪拌され、均一な組成が要求される合金溶解に適している。
【０００３】
図８は従来例の構成図を示す。この図８において、コールドクルーシブル溶解装置は、１つの電源に繋がれた円形のコイル２の内側に、電気的に絶縁された２つ以上のセグメント３をスリット３ａを介してコイル２の周方向に並べて水冷金属るつぼ１を構成している。また水冷金属るつぼ底部は水冷金属やグラファイト等の断熱材で構成されている。水冷金属るつぼ１内部には金属材料が入れられる。
【０００４】
水冷金属るつぼ１を構成するセグメント３は水等により加熱されないように冷却される。
高周波電源５から供給されるコイル２の電流は、スリット３ａにより電気的に絶縁されたそれぞれのセグメント３にうず電流を誘導するとともに、金属材料にもうず電流を誘導し、金属材料は抵抗損により加熱し続けられ溶解されて溶湯４になる。この水冷金属るつぼ１と溶湯４に流れるうず電流の方向は対向面で互いに逆向きなので磁気的に反発力となり、水冷金属るつぼ１は固定されているので溶湯４に働く反発力が溶湯４の重量より大きければ溶湯４は水冷金属るつぼ１の側面から離れる。このため溶湯４はるつぼ底部が接触しるつぼ側面は溶湯静圧と電磁反発力がバランスする位置（σ［ｋｇ／ｍ³］×ｈ［ｍ］＝Ｆ［ｋｇ／ｍ²］）より下部では水冷金属るつぼ１と接触した状態で溶解する。
【０００５】
ここで、
σ：溶湯の単位体積当たり重量［ｋｇ／ｍ³］
ｈ：溶湯へツド（上面からの高さ）［ｍ］
Ｆ：溶湯表面に働く電磁反発力［ｋｇ／ｍ²］である。
【０００６】
コールドクルーシブル誘導加熱溶解法はるつぼ材からの不純物混入が無いため、純チタンやＴｉ−６Ａｌ−４Ｖ等のチタン合金等の溶解に用いられている。この方式の場合、σｈ＞Ｆになる溶湯の深さから下部では溶湯は水冷金属るつぼと接触するため水冷金属るつぼへの抜熱があることから溶解能力としては溶湯温度が１９００℃〜２０００℃以下の金属に限定されている。
【０００７】
【発明が解決しようとする課題】
溶湯温度が１９００℃を超えた金属を溶解する場合、上記方式では水冷金属るつぼとの接触による抜熱の影響によって溶解が困難である。また溶湯温度が１９００℃を超える合金、および純金属の殆どはその密度が１０ｇ／ｃｍ³ を超えているためチタンの密度４．１ｇ／ｃｍ³と同容積の材料を溶解した場合と比較するとるつぼ側面の電磁反発力がバランスする位置はチタンでの非接触高さの半分以下となるため、るつぼへの披熱量はるつぼの接触面積に比例することから、当然るつぼへの抜熱量が増大し、溶解に要するエネルギーを増大させなければ金属を溶解することが出来ない。この問題は、従来技術で溶解可能な金属の場合においても、るつぼ容量を従来最大溶解量の数１００ｋｇからさらに増大させる場合においても、同様にるつぼの披熱量を低減させることが必要となることを示している。
【０００８】
ここで図８の従来例の１コイル式装置について、金属の溶解能力に応じて設定されている運転周波数ｆ１と電源容量Ｐ１とを用いて溶湯に作用する電磁反発力Ｆ１を電磁解析して、該電磁反発力Ｆ１と、溶湯静圧ｄｈとのバランス状態を図９（ａ）、（ｂ）に示す。図９（ａ）は溶湯に作用する電磁反発力と溶湯静圧とのバランス状態を模擬的に示した水冷金属るつぼの断面図、（ｂ）は溶湯表面から底部までの高さ（深さ）を横軸に、溶湯高さｄｈと該ｄｈ各位置で溶湯に作用する電磁反発力Ｆ１とを縦軸方向に表した図である。この図９（ｂ）において、溶湯静圧ｄｈと電磁反発力Ｆ１とが交わる高さｈ１以降では溶湯とるつぼ側壁とが接触しており、そこからの抜熱による影響で溶解温度、もしくは溶解量に上限が生じる。
【０００９】
なお、図９（ａ）は前記ｈ１を水冷金属るつぼの断面図中に記載したものである。そこで、従来例では溶解困難な高融点金属や溶解量を従来より増大させることを目的として、従来例の１コイル式装置を用い水冷金属るつぼへの接触量を低減させるために溶湯静圧に打ち勝つ運転周波数（従来例より低くして電磁反発力を増大させる周波数）を選択すると、溶解金属への投入電力が周波数の低下に応じて減少することが起こり、これを補うためにはコイルへの通電電流を増加させなければならないが、コイルでの銅損を冷却する際の冷却効果の問題から通電電流には限界があり、必用な通電電流が得られない場合は加熱効果が低減し、例えば鋳造に必用なスーパーヒート（溶解金属の融点に対する昇温値）が十分に確保できなくなる可能性がある。一方コイルへの通電電流を増大させず、溶解材料への投入電力を増大させるために運転周波数を高く設定すると、今度は金属表面に作用する電磁反発力が小さくなるため、るつぼへの接触面積が上昇し、るつぼへの抜熱量が増え電源容量をさらに増大させる必要が生じる。しかし電源容量の増大はるつぼ自身の冷却効果を高める構造とする必要が生じ、るつぼ構造上冷却性能を満足できる電源容量にも上限があることから必然的に溶解量、および溶解温度に上限が生じてしまう。
【００１０】
この発明は上記の課題を解決するために、溶解金属側面で水冷金属るつぼとの接触を低減し、水冷金属るつぼへの抜熱を減少させることにより、溶解量の増大、および密度が大きい金属や、高融点金属の溶解を可能にするコールドクルーシブル溶解鋳造装置を提供することにある。
【００１１】
【課題を解決するための手段】
上記課題を解決するために請求項１の発明は、円形のコイルの内側に電気的に絶縁された２つ以上のセグメントを前記コイルの周方向に並べて水冷金属るつぼを構成し、高周波電源を用いて前記コイルを励磁し、水冷金属るつぼ中の金属材料を誘導加熱溶解し、前記金属材料が溶解された溶湯と前記水冷金属るつぼとの間にスカルを形成するコールドクルーシブル溶解装置であって、水冷金属るつぼ内で溶解した金属を前記水冷金属るつぼの傾転によって前記水冷金属るつぼ下部に据え付けた鋳型に鋳造するコールドクルーシブル溶解鋳造装置において、前記コイルは前記水冷金属るつぼ外周の上下に２段に設けるとともに、前記金属材料の溶解時に上コイルに通電する電流の周波数を下コイルに通電する電流の周波数より低くすることを特徴とする。
【００１２】
ここで、周波数と溶湯表面に誘起する電力、および周波数と溶湯表面に作用する電磁反発力との関係は、コイル内に生じる交番磁界が溶湯に沿っている場合（即ち浸透深さが溶湯の大きさと比較して十分に小さい場合）には、溶湯への投入電力ｗは次式で与えられる。
ｗ＝１／２（πｆμρ）^1/2 ・Ｈｍ² （１）
ｗ：溶湯への投入電力［ｗ］
f：運転周波数［Ｈｚ］
μ：金属の透磁率［Ｈ／ｍ］
ρ：金属の抵抗率［Ω・ｍ］
Ｈｍ：溶湯表面に沿う磁界強度［ＡＴ／ｍ］
【００１３】
一方、溶湯表面に作用する電磁反発力Ｆは次式で与えられる。
Ｆ＝１／２（μＨｍ² ）（２）
上式より電磁反発力Ｆと投入電力ｗの関係は次式で与えられる。
Ｆ＝Ｗ（μ／πｆρ）^1/2 （３）
この式は溶湯に投入される電力量が一定の時、周波数が低いほど電磁反発力が大きいことを示している。
【００１４】
ここで、るつぼ側壁と溶湯との接触を減少させる目的でコイルを上下２段にして上コイルは従来例の運転周波数ｆ１より低い運転周波数ｆ２と電源容量Ｐ２とに設定し、下コイルはｆ１より高い運転周波数ｆ３と、上コイルの運転周波数をｆ２に下げたことによる投入電力の低下を下コイルの運転周波数ｆ３を高くすることでるつぼ側壁と溶湯とが接触する部分には従来例の１コイル式装置より高い発熱が生じる電源容量Ｐ３に設定し合計ではＰ２＋Ｐ３＝Ｐ１（従来例の運転周波数ｆ１のときの電源容量）になるように設定して電磁解析を行い、その結果を図２（ａ）、（ｂ）に示す。
【００１５】
図２（ａ）は溶湯に作用する電磁反発力と溶湯静圧とのバランス状態を模擬的に示した水冷金属るつぼの断面図、（ｂ）は溶湯表面から底部までの高さ（深さ）を横軸に、溶湯高さｄｈと、該ｄｈ各位置で溶湯に作用する電磁反発力Ｆ２，Ｆ３とを縦軸方向に表した図である。この図２（ｂ）において、溶湯静圧ｄｈと電磁反発力Ｆ２とが交わる高さｈ２以降では溶湯とるつぼ側壁とが接触しているが、上コイルにより溶湯に作用する電磁反発力Ｆ２は従来例のＦ１より大きくなっているので、溶湯とるつぼ側壁とが接触する位置ｈ２はｈ１より下方に下げられている。
【００１６】
なお、図２（ａ）は前記ｈ２を水冷金属るつぼの断面図中に記載したものである。従って請求項１の構成により、図２（ａ），（ｂ）に示すように上コイルには従来例の周波数ｆ１より低い周波数ｆ２の高周波電流を通電して、従来例の周波数ｆ１に対応する電磁反発力Ｆ１より強いＦ２なる電磁反発力を生じさせることにより水冷金属るつぼと溶湯との接触位置をｈ１からｈ２に下げ、下コイルには従来例の周波数ｆ１より高い周波数ｆ３の高周波電流を通電することにより、電磁反発力Ｆ３は従来例のＦ１より小さくなるが電力投入密度は周波数が高い分大きくすることができる。これら水冷金属るつぼと、溶湯との接触位置を下げること、および下コイルでの電力投入密度を大きくして水冷金属るつぼへの抜熱を補うことにより、従来例より溶解量を増大させること、および高融点の金属を溶解することが可能になる。
【００１７】
また、請求項２の発明のように、円形のコイルの内側に電気的に絶縁された２つ以上のセグメントを前記コイルの周方向に並べて水冷金属るつぼを構成し、高周波電源を用いて前記コイルを励磁し、水冷金属るつぼ中の金属材料を誘導加熱溶解し、前記金属材料が溶解された溶湯と前記水冷金属るつぼとの間にスカルを形成するコールドクルーシブル溶解装置であって、前記水冷金属るつぼ内で溶解した金属を前記水冷金属るつぼの底部に直結した水冷製の鋳型に鋳造するコールドクルーシブル溶解鋳造装置において、前記コイルは前記水冷金属るつぼ外周の上下に２段に設けるとともに、前記金属材料の溶解時に上コイルに通電する電流の周波数を下コイルに通電する電流の周波数より低くするようにしても良い。
【００１８】
また、請求項３の発明は、円形のコイルの内側に電気的に絶縁された２つ以上のセグメントを前記コイルの周方向に並べて水冷金属るつぼを構成し、高周波電源を用いて前記コイルを励磁し、水冷金属るつぼ中の金属材料を誘導加熱溶解し、前記金属材料が溶解された溶湯と前記水冷金属るつぼとの間にスカルを形成するコールドクルーシブル溶解装置であって、前記水冷金属るつぼ内で溶解した金属を前記水冷金属るつぼの底部に直結した水冷製の鋳型に鋳造するコールドクルーシブル溶解鋳造装置において、前記コイルは前記水冷金属るつぼ外周の上下に２段に設けるとともに、前記金属材料の溶解時に上コイルに通電する電流の周波数を下コイルに通電する電流の周波数より低くすることを特徴とする。
【００１９】
また、請求項４の発明のように、請求項３に記載のコールドクルーシブル溶解鋳造装置において、水冷金属るつぼ底部に溶解した金属の落下を防止する引抜駆動栓を設けて、該栓の引抜駆動により鋳造を行うことができる。また、請求項５の発明のように、請求項４記載のコールドクルーシブル溶解鋳造装置において、引抜駆動栓が水冷機能を有しており、先端部分が取り外し交換可能な水冷金属製で作ることができる。
【００２０】
また、請求項６の発明のように、請求項４または請求項５に記載のコールドクルーシブル溶解鋳造装置において、引抜駆動栓の上部に材質が溶解した金属と同種類のとも材で作られた、引抜駆動栓とは着脱可能に取付けられるとも材栓を設けることができる。上記の請求項３から請求項６の発明の構成により、水冷金属るつぼで溶解した金属を、引抜駆動栓を介して冷却された前記溶解した金属と同じ材質のとも材栓に凝着させて、るつぼの下部に直結した鋳型に引き込み、該鋳型で冷却凝固させることにより、不純物などの混入が無い鋳塊を製造することが可能になる。
【００２１】
【発明の実施の形態】
図１はこの発明の実施の形態の主要部の構成図を示す。この図１において、従来例と同一の符号を付けた部材はおおよそ同一の機能を有するのでその説明は省略する。この図１において、コールドクルーシブル溶解装置は、高周波電源５に接続された円形の上コイル２ａ、および高周波電源５より高い周波数の高周波電源６に接続された、上コイル２ａとほぼ同じ内径を有する下コイル２ｂの内側に、電気的に絶縁された２つ以上のセグメント３をスリット３ａを介して上下コイル２ａ、２ｂの周方向に並べて水冷金属るつぼ１を構成している。また水冷金属るつぼ１底部はセグメント３と同じ材質の金属で構成されている。水冷金属るつぼ１内部には金属材料が入れられる。水冷金属るつぼ１を構成するセグメント３は水等により加熱されないように冷却される。
【００２２】
高周波電源５から供給される上コイル２ａ、および高周波電源６から供給される下コイル２ｂの電流は、それぞれスリット３ａにより電気的に絶縁されたセグメント３にうず電流を誘導するとともに、金属材料にもうず電流を誘導し、金属材料は抵抗損により加熱し続けられ溶解されて溶湯４になる。
この水冷金属るつぼ１と溶湯４に流れるうず電流の方向は対向面では互いに逆向きなので磁気的に反発力となり、水冷金属るつぼ１は固定されているので溶湯４に働く反発力が溶湯４の重量より大きければ溶湯４は水冷金属るつぼ１の側面から離れる。
【００２３】
ここで、上コイル２ａに供給される電流の周波数は下コイル２ｂに供給される電流の周波数より低い値に設定されているので、図２に示すように溶湯４と水冷金属るつぼ１の側壁とが接触する位置はｈ２になり、水冷金属るつぼ１への抜熱量が軽減されるようになっている。
図３は請求項１の発明の実施の形態の主要部の構成図を示す。この図３において、図１の構成とほぼ同じ構成の水冷金属るつぼ１は傾転中心を中心として傾転可能な傾転手段を有しており、水冷金属るつぼ１内で溶解された金属は前記傾転手段により傾転される水冷金属るつぼ１上端部から出湯されて鋳型７に鋳造される。なお、この例では水冷金属るつぼ１、および鋳型７はチャンバーとよばれる溶解鋳造室内に収納されており所望の雰囲気中での溶解および鋳造が可能な構造になっている。
【００２４】
図４は請求項２の発明の実施の形態の主要部の構成図を示す。この図４において、水冷金属るつぼ１は図１の構成とほぼ同じ構成となっているのでその説明は省略する。この図４が図３と異なる点は水冷金属るつぼ１で溶解した金属（溶湯４）を水冷金属るつぼ１の傾転により出湯して鋳型に鋳込む代りに溶湯４に浸漬したノズルに直結した鋳型８を設けて該鋳型８を吸引装置の中に設置して吸引装置によりノズルを介して吸引した溶湯４を鋳型８に鋳造するようにした点である。
【００２５】
図５は請求項３の発明の実施の形態の主要部の構成図を示す。この図５において、コールドクルーシブル溶解装置は、高周波電源５に接続された円形の上コイル２ａ、および高周波電源５より高い周波数の高周波電源６に接続された、上コイル２ａとほぼ同じ内径を有する下コイル２ｂの内側に、電気的に絶縁された２つ以上のセグメント３をスリット３ａを介して上下コイル２ａ、２ｂの周方向に並べて水冷金属るつぼ１を構成している。また水冷金属るつぼ１底部は胴部と同じ径の底穴になっている。水冷金属るつぼ１内部には金属材料が入れられ、該水冷金属るつぼ１内で溶解されて溶湯４になる。水冷金属るつぼ１を構成するセグメント３は水等により加熱されないように冷却される。
【００２６】
該水冷金属るつぼ１の底部には、水冷製で上部にスリットが入った鋳型１０が直結され、その下部に引抜鋳造装置１５が設けられている。前記水冷金属るつぼ１の底穴には該底穴に嵌合され、下部で水冷機能を有したとも材栓１２、および該とも材栓１２を駆動する引抜駆動栓１１、引抜駆動部昇降台１４が引抜駆動装置１３に直結して設けられている。
【００２７】
図５において、引抜駆動時に溶湯４は鋳型１０中で凝固するよう電源電力、引抜速度、引抜駆動栓１１及び水冷鋳型１０の冷却が制御されるため所望の引抜鋳造が行える。水冷金属るつぼ１と鋳型１０は双方とも金属製の場合、運転時の両者間での短絡や放電による損傷を避ける為、電気的に絶縁されるよう微少な空間を有した構造とするか、水冷金属るつぼ１と鋳型１０との接触面に薄い絶縁物が挿入されていることが望ましい。
【００２８】
金属材料溶解時、引抜駆動栓１１は水冷金属るつぼ１の底穴に嵌合されている。引抜駆動時にるつぼ底穴付近の溶湯４と引抜駆動栓１１の先端部が半溶融状態を形成する様にする場合、引抜駆動栓１１の先端には溶湯４と同じ材質のとも材栓１２を使用し、そのとも材栓１２は水冷されていないが、下部で冷却された引抜駆動栓１１からの接触熱伝達で水冷される様な構造となっている。引抜駆動時は鋳型１０の位置を固定し、引抜駆動装置１３を駆動して引抜駆動栓１１、およびとも材栓１２の駆動を行う。この場合の引抜駆動は、引抜開始時に上方向に駆動してから引下げを行ったり、引抜鋳造時には、連続的下引動作、間欠的下引動作、上下方向への可逆動作等、種々の方案が考えられるが、鋳型１０中で溶湯４を連続的に凝固させて引抜きを行う。鋳型１０中の溶湯４は溶解時は鋳型１０からも抜熱を受けるが凝固により容積が収縮するため、鋳型１０に接触せずに引抜きが行えるが、鋳型１０内径を下部はテーパ状に広げたものを使用条件によって使い分ける。
【００２９】
引抜駆動時にとも材栓を使用しないで引抜駆動栓１１上部で軟接触状態とし、引抜駆動後に栓上部の凝固層を再溶解し出湯鋳造する場合、引抜駆動栓１１は栓の上部まで水冷された銅製栓を使用する。この場合、るつぼ底穴付近は引抜駆動栓への抜熱により再凝固層が形成されるが、引抜駆動栓１１の引下げによって抜熱が無くなることと、底部に磁束が侵入することによって再凝固層に渦電流が流れる様になるため、再凝固層を溶解し出湯することが可能である。この場合は１ショットによる鋳造となるが従来より出湯ストロークが短くなる利点が挙げられる。
【００３０】
鋳型１０は溶湯４が凝固した金属への不純物混入を避ける為には、水冷された金属製が望ましい。また鋳造時の制御を行う為に、図示していないコイルを鋳型１０周囲に巻くこともでき、鋳型１０にはコイルの巻かれている位置よりも下部にスリットが入った構造とすることにより、凝固時の温度制御や鋳型への接触等を制御する構成とすることができる。
【００３１】
図６、図７は図５の発明のコールドクルーシブル溶解鋳造装置を雰囲気制御下で行えるようにした例の構成図で、図６は鋳造前の状態図、図７は鋳造中の状態図を示す。この図６、図７が図５と異なる点は図５が大気中での溶解鋳造としている代りに、水冷金属るつぼ１、および上下コイル２ａ、２ｂ、鋳型１０、とも材栓１２、引抜駆動栓１１、引抜鋳造装置１５を真空ポンプ、および雰囲気制御装置を備えた真空チャンバー１６内に収納するとともに、引抜鋳造装置１５の可動部を引抜駆動部昇降台と真空チャンバー１６との間で伸縮可能に密閉して真空状態が保てるようにした伸縮可能なベローズ１７等で接続した点である。
【００３２】
このように構成することにより、真空下、もしくは不活性ガス雰囲気下での溶解鋳造が可能になり、溶解材料からの脱ガス、および溶解鋳造時の金属の酸化防止が行える。
【００３３】
【発明の効果】
この発明によれば、水冷るつぼ外周に巻かれるコイルが周波数の異なる２つ以上のコイルを有し、水冷るつぼ上部側のコイルには電磁力特性に優れる低い周波数を採用することでるつぼとの接触面積を低減してるつぼへの抜熱量を減らすことができ、水冷るつぼ下部のコイルには加熱特性に優れる上コイルよりも高い周波数を採用することで溶解金属の加熱を積極的に行い溶湯下部の凝固を抑制することができる。また上下のコイルは各々独自で電力制御することが可能となるので、従来のコールドクルーシブル溶解鋳造装置で困難だった高融点金属や合金の溶解及び鋳造品鋳造や従来装置で溶解可能な金属において溶解量を従来より増大させた場合においても溶解と鋳造品鋳造の対応が可能になる。
【図面の簡単な説明】
【図１】この発明の実施の形態の主要部の構成図
【図２】（ａ）は溶湯に作用する電磁反発力と溶湯静圧とのバランス状態を模擬的に示した水冷金属るつぼの断面図、（ｂ）は溶湯表面から底部までの高さ（深さ）を横軸に、溶湯高さｄｈと、該ｄｈ各位置で溶湯に作用する電磁反発力Ｆ２，Ｆ３とを縦軸方向に表した図
【図３】請求項１の発明の実施の形態の主要部の構成図
【図４】請求項２の発明の実施の形態の主要部の構成図
【図５】請求項３の発明の実施の形態の主要部の構成図
【図６】図５の発明のコールドクルーシブル溶解鋳造装置を雰囲気制御下で行えるようにした例の構成図で、鋳造前の状態図
【図７】図６の鋳造中の状態図
【図８】従来例の構成図
【図９】（ａ）は図８の構成で溶湯に作用する電磁反発力と溶湯静圧とのバランス状態を模擬的に示した水冷金属るつぼの断面図、（ｂ）は図８の構成で溶湯表面から底部までの高さ（深さ）を横軸に、溶湯高さｄｈと、該ｄｈ各位置で溶湯に作用する電磁反発力Ｆ１とを縦軸方向に表した図
【符号の説明】
１水冷金属るつぼ
２ａ上コイル
２ｂ下コイル
５、６高周波電源
７、８、１０鋳型
９吸引装置
１１引抜駆動栓
１２とも材栓
１５引抜鋳造装置
１６真空チャンバー
１７ベローズ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cold crucible melting and casting apparatus in which a coil is excited using a high frequency power source, a metal material in a water-cooled metal crucible is induction-heated and melted, and a molten metal is cast into a mold.
[0002]
[Prior art]
The cold crucible melting device is a device in which a high frequency induction coil is wound around a water-cooled metal crucible. When a metal is placed inside a water-cooled metal crucible and a high frequency current is passed through the coil, an eddy current is induced in the metal, and the metal is heated and melted. Since the metal melted by this method is not mixed with impurities from the water-cooled metal crucible, a high-purity molten metal can be formed. Further, by casting this molten metal in a mold, it is possible to produce a high-purity cast product, which is suitable for melting active metals such as titanium, refractory metals (chromium, niobium, molybdenum), silicon and the like. In addition, since the electromagnetic force acting on the water-cooled metal crucible is strong, the molten metal is electromagnetically stirred and is suitable for melting an alloy that requires a uniform composition.
[0003]
FIG. 8 shows a configuration diagram of a conventional example. In FIG. 8, the cold crucible melting apparatus has two or more electrically insulated segments 3 in the circumferential direction of the coil 2 via slits 3a inside a circular coil 2 connected to one power source. A water-cooled metal crucible 1 is formed side by side. The bottom of the water-cooled metal crucible is made of a heat-insulating material such as water-cooled metal or graphite. A metal material is placed inside the water-cooled metal crucible 1.
[0004]
The segment 3 constituting the water-cooled metal crucible 1 is cooled so as not to be heated by water or the like.
The current of the coil 2 supplied from the high frequency power source 5 induces eddy current in each segment 3 electrically insulated by the slit 3a and induces eddy current in the metal material. It is continuously heated and melted to form molten metal 4. Since the directions of the eddy currents flowing in the water-cooled metal crucible 1 and the molten metal 4 are opposite to each other on the opposing surfaces, they are magnetically repulsive, and since the water-cooled metal crucible 1 is fixed, the repulsive force acting on the molten metal 4 is the weight of the molten metal 4. If larger, the molten metal 4 moves away from the side surface of the water-cooled metal crucible 1. For this reason, the molten metal 4 is water-cooled below the position (σ [kg / m ³ ] × h [m] = F [kg / m ² ]) where the molten metal static pressure and the electromagnetic repulsive force are balanced on the side of the crucible where the bottom of the crucible contacts. Dissolves in contact with the metal crucible 1.
[0005]
here,
σ: Weight per unit volume of molten metal [kg / m ³ ]
h: Melt head (height from the top) [m]
F: Electromagnetic repulsive force [kg / m ² ] acting on the molten metal surface.
[0006]
The cold crucible induction heating melting method is used for melting pure titanium, titanium alloys such as Ti-6Al-4V, and the like because no impurities are mixed from the crucible material. In the case of this method, since the molten metal comes into contact with the water-cooled metal crucible at the lower part from the depth of the molten metal satisfying σh> F, the molten metal temperature is 1900 ° C. to 2000 ° C. or less because the heat is removed to the water-cooled metal crucible. Limited to metals.
[0007]
[Problems to be solved by the invention]
When melting a metal having a molten metal temperature exceeding 1900 ° C., it is difficult to dissolve the metal due to the effect of heat removal due to contact with the water-cooled metal crucible. Also, most of the alloys whose molten metal temperature exceeds 1900 ° C. and pure metals have a density exceeding 10 g / cm ³ , so that the crucible is compared with the case where a material having the same volume as the titanium density of 4.1 g / cm ³ is melted. Since the position where the electromagnetic repulsive force on the side balances is less than half of the non-contact height with titanium, the amount of heat presented to the crucible is proportional to the contact area of the crucible, so the amount of heat removed to the crucible naturally increases, The metal cannot be dissolved unless the energy required for melting is increased. The problem is that, even in the case of metals that can be melted by the prior art, even when the crucible capacity is further increased from the conventional maximum melting amount of several hundred kg, it is necessary to similarly reduce the amount of heat displayed in the crucible. Show.
[0008]
Here, the electromagnetic repulsive force F1 acting on the molten metal using the operating frequency f1 and the power source capacity P1 set according to the melting ability of the metal is electromagnetically analyzed for the conventional one-coil device of FIG. FIGS. 9A and 9B show a balance state between the electromagnetic repulsion force F1 and the molten metal static pressure dh. 9A is a cross-sectional view of a water-cooled metal crucible simulating the balance between the electromagnetic repulsive force acting on the molten metal and the static pressure of the molten metal, and FIG. 9B is the height (depth) from the molten metal surface to the bottom. Is the horizontal axis, and the molten metal height dh and the electromagnetic repulsive force F1 acting on the molten metal at each position of the dh are shown in the vertical axis direction. In FIG. 9 (b), the crucible side wall where the molten metal is taken is in contact after the height h1 where the molten metal static pressure dh and the electromagnetic repulsive force F1 intersect, and the melting temperature or the amount of melting is affected by the heat removal from there. An upper limit occurs.
[0009]
In addition, Fig.9 (a) has described said h1 in sectional drawing of a water-cooled metal crucible. Therefore, in order to reduce the amount of contact with the water-cooled metal crucible by using the conventional one-coil type device for the purpose of increasing the refractory metal that is difficult to dissolve in the conventional example and the amount of dissolution, it is possible to overcome the static pressure of the molten metal. When the operating frequency (frequency that lowers the electromagnetic repulsion force by lowering the conventional example) is selected, the input power to the molten metal may decrease as the frequency decreases. To compensate for this, the coil is energized. Although the current must be increased, there is a limit to the energizing current due to the cooling effect when cooling the copper loss in the coil, and if the necessary energizing current cannot be obtained, the heating effect is reduced, for example, casting There is a possibility that the superheat (temperature rise value relative to the melting point of the molten metal) necessary for the heat treatment cannot be secured sufficiently. On the other hand, if the operating frequency is set high in order to increase the electric power applied to the melted material without increasing the energizing current to the coil, the electromagnetic repulsive force acting on the metal surface is reduced this time, so that the contact area to the crucible is reduced. As a result, the amount of heat extracted from the crucible increases and the power source capacity needs to be further increased. However, an increase in power supply capacity requires a structure that enhances the cooling effect of the crucible itself, and since there is an upper limit to the power supply capacity that can satisfy the cooling performance on the crucible structure, an upper limit is inevitably generated in the melting amount and the melting temperature. End up.
[0010]
In order to solve the above-mentioned problems, the present invention reduces the contact with the water-cooled metal crucible on the side of the molten metal and reduces the heat removal to the water-cooled metal crucible, thereby increasing the amount of dissolution, Another object of the present invention is to provide a cold crucible melting and casting apparatus that enables melting of a refractory metal.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 is characterized in that a water-cooled metal crucible is formed by arranging two or more segments electrically insulated inside a circular coil in the circumferential direction of the coil, and a high-frequency power source is used. A cold-crucible melting device that excites the coil, inductively heats and melts the metal material in the water-cooled metal crucible, and forms a skull between the molten metal in which the metal material is melted and the water-cooled metal crucible, In a cold crucible melting casting apparatus in which a metal melted in a metal crucible is cast into a mold mounted on the lower part of the water-cooled metal crucible by tilting the water-cooled metal crucible, the coil is provided in two stages above and below the outer periphery of the water-cooled metal crucible In addition, the frequency of the current applied to the upper coil when the metal material is melted is set lower than the frequency of the current applied to the lower coil. To.
[0012]
Here, the relationship between the frequency and the electric power induced on the surface of the molten metal and the frequency and the electromagnetic repulsive force acting on the surface of the molten metal are determined when the alternating magnetic field generated in the coil is along the molten metal (that is, the penetration depth is larger than the molten metal). In the case where the electric power w is sufficiently small compared to the above, the input electric power w to the molten metal is given by the following equation.
w = ^1/2 (πfμρ) ^1/2 · Hm ² (1)
w: Input power to molten metal [w]
f: Operating frequency [Hz]
μ: Magnetic permeability of metal [H / m]
ρ: Metal resistivity [Ω · m]
Hm: Magnetic field strength along the molten metal surface [AT / m]
[0013]
On the other hand, the electromagnetic repulsive force F acting on the molten metal surface is given by the following equation.
F = 1/2 (μHm ² ) (2)
From the above equation, the relationship between the electromagnetic repulsive force F and the input power w is given by the following equation.
F = W (μ / πfρ) ^1/2 (3)
This equation indicates that when the amount of power supplied to the molten metal is constant, the lower the frequency, the greater the electromagnetic repulsion force.
[0014]
Here, in order to reduce the contact between the crucible side wall and the molten metal, the upper coil is set to an operating frequency f2 lower than the operating frequency f1 of the conventional example and the power source capacity P2, and the lower coil is set to f1. In the portion where the crucible side wall and the molten metal come into contact with each other by increasing the operating frequency f3 of the lower coil to reduce the input power due to the high operating frequency f3 and lowering the operating frequency of the upper coil to f2, one coil of the conventional example Electromagnetic analysis is performed by setting the power source capacity P3 that generates heat higher than that of the formula apparatus and setting the total so that P2 + P3 = P1 (the power source capacity at the operation frequency f1 of the conventional example), and the result is shown in FIG. ) And (b).
[0015]
2A is a cross-sectional view of a water-cooled metal crucible simulating the balance between the electromagnetic repulsion force acting on the molten metal and the molten metal's static pressure, and FIG. 2B is the height (depth) from the molten metal surface to the bottom. Is a graph in which the molten metal height dh and the electromagnetic repulsive forces F2 and F3 acting on the molten metal at each position of the dh are represented in the vertical axis. In FIG. 2B, the crucible side wall is in contact with the crucible side wall after the height h2 at which the molten metal static pressure dh and the electromagnetic repulsive force F2 intersect, but the electromagnetic repulsive force F2 acting on the molten metal by the upper coil is conventional. Since it is larger than F1 in the example, the position h2 where the molten metal and the crucible side wall are in contact with each other is lowered below h1.
[0016]
FIG. 2A shows h2 in a cross-sectional view of a water-cooled metal crucible. Therefore, according to the structure of claim 1, as shown in FIGS. 2A and 2B, the upper coil is supplied with a high-frequency current having a frequency f2 lower than the frequency f1 of the conventional example, and corresponds to the frequency f1 of the conventional example. By generating an electromagnetic repulsive force F2 stronger than the electromagnetic repulsive force F1, the contact position between the water-cooled metal crucible and the molten metal is lowered from h1 to h2, and the lower coil is energized with a high-frequency current having a frequency f3 higher than the conventional frequency f1. By doing so, the electromagnetic repulsion force F3 becomes smaller than F1 of the conventional example, but the power input density can be increased by the higher frequency. By lowering the contact position between these water-cooled metal crucibles and the molten metal, and increasing the power input density in the lower coil to compensate for heat removal to the water-cooled metal crucible, the amount of dissolution is increased from the conventional example, and It becomes possible to dissolve a high melting point metal.
[0017]
According to a second aspect of the present invention, a water-cooled metal crucible is formed by arranging two or more segments electrically insulated inside a circular coil in the circumferential direction of the coil, and the coil is formed using a high frequency power source. A cold-crucible melting apparatus that forms a skull between the molten metal in which the metal material is melted and the water-cooled metal crucible, wherein the metal material in the water-cooled metal crucible is formed by induction heating and melting. In the cold crucible melting and casting apparatus for casting the metal melted in a water-cooled mold directly connected to the bottom of the water-cooled metal crucible, the coil is provided in two stages above and below the outer periphery of the water-cooled metal crucible, The frequency of the current applied to the upper coil during melting may be set lower than the frequency of the current applied to the lower coil.
[0018]
According to a third aspect of the present invention, a water-cooled metal crucible is formed by arranging two or more segments electrically insulated inside a circular coil in the circumferential direction of the coil, and the coil is excited using a high frequency power source. A cold-crucible melting apparatus for melting a metal material in a water-cooled metal crucible by induction heating and forming a skull between the molten metal in which the metal material is melted and the water-cooled metal crucible, In the cold crucible melting and casting apparatus for casting the molten metal into a water-cooled mold directly connected to the bottom of the water-cooled metal crucible, the coil is provided in two stages above and below the outer periphery of the water-cooled metal crucible, and when the metal material is melted The frequency of the current flowing through the upper coil is made lower than the frequency of the current flowing through the lower coil.
[0019]
According to a fourth aspect of the present invention, in the cold crucible melting and casting apparatus according to the third aspect, a pull-out driving plug is provided to prevent the molten metal from falling at the bottom of the water-cooled metal crucible. Casting can be performed. Further, as in the invention of claim 5, in the cold crucible melting and casting apparatus according to claim 4, the pull-out drive plug has a water cooling function, and the tip portion can be made of a water-cooled metal that can be removed and replaced. .
[0020]
Further, as in the invention of claim 6, in the cold crucible melting and casting apparatus according to claim 4 or claim 5, the upper part of the pull-out driving plug is made of the same kind of metal as the metal melted, The pull-out driving plug can be detachably mounted and can be provided with a material plug. According to the configuration of the invention of claims 3 to 6 described above, the metal melted in the water-cooled metal crucible is adhered to the material plug of the same material as the melted metal cooled through the pull-out driving plug, By drawing into a mold directly connected to the lower part of the crucible and cooling and solidifying with the mold, it becomes possible to produce an ingot free from impurities.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing the main part of an embodiment of the present invention. In FIG. 1, members denoted by the same reference numerals as those in the conventional example have approximately the same functions, and thus description thereof is omitted. In FIG. 1, the cold crucible melting device has a circular upper coil 2a connected to the high frequency power source 5 and a lower coil having substantially the same inner diameter as the upper coil 2a connected to the high frequency power source 6 having a higher frequency than the high frequency power source 5. Inside the coil 2b, two or more electrically insulated segments 3 are arranged in the circumferential direction of the upper and lower coils 2a, 2b via the slit 3a to constitute the water-cooled metal crucible 1. The bottom of the water-cooled metal crucible 1 is made of the same material as the segment 3. A metal material is placed inside the water-cooled metal crucible 1. The segment 3 constituting the water-cooled metal crucible 1 is cooled so as not to be heated by water or the like.
[0022]
The currents of the upper coil 2a supplied from the high-frequency power source 5 and the lower coil 2b supplied from the high-frequency power source 6 induce eddy currents in the segments 3 electrically insulated by the slits 3a, respectively, and are already applied to the metal material. An electric current is induced, and the metal material is continuously heated by resistance loss and melted to become a molten metal 4.
The directions of the eddy currents flowing in the water-cooled metal crucible 1 and the molten metal 4 are opposite to each other on the opposing surfaces, so that they are magnetically repulsive, and since the water-cooled metal crucible 1 is fixed, the repulsive force acting on the molten metal 4 is the weight of the molten metal 4 If larger, the molten metal 4 moves away from the side surface of the water-cooled metal crucible 1.
[0023]
Here, since the frequency of the current supplied to the upper coil 2a is set to a value lower than the frequency of the current supplied to the lower coil 2b, the molten metal 4 and the side wall of the water-cooled metal crucible 1 as shown in FIG. The position where the contact is h2 is that the amount of heat removed to the water-cooled metal crucible 1 is reduced.
FIG. 3 is a block diagram showing the main part of the embodiment of the first aspect of the present invention. In FIG. 3, a water-cooled metal crucible 1 having substantially the same configuration as that of FIG. 1 has tilting means that can tilt around the tilt center, and the metal dissolved in the water-cooled metal crucible 1 Hot water is discharged from the upper end of the water-cooled metal crucible 1 tilted by the tilting means and cast into the mold 7. In this example, the water-cooled metal crucible 1 and the mold 7 are housed in a melting and casting chamber called a chamber, and have a structure capable of melting and casting in a desired atmosphere.
[0024]
FIG. 4 shows a configuration diagram of the main part of the embodiment of the invention of claim 2. In FIG. 4, the water-cooled metal crucible 1 has substantially the same configuration as that of FIG. 4 differs from FIG. 3 in that the metal (molten metal 4) melted in the water-cooled metal crucible 1 is poured by the tilt of the water-cooled metal crucible 1 and cast directly into the mold instead of being cast into the mold. 8, the mold 8 is placed in a suction device, and the molten metal 4 sucked through the nozzle by the suction device is cast into the mold 8.
[0025]
FIG. 5 shows a configuration diagram of the main part of the embodiment of the invention of claim 3. In FIG. 5, the cold crucible melting apparatus has a circular upper coil 2 a connected to the high frequency power source 5 and a lower coil having substantially the same inner diameter as the upper coil 2 a connected to the high frequency power source 6 having a higher frequency than the high frequency power source 5. Inside the coil 2b, two or more electrically insulated segments 3 are arranged in the circumferential direction of the upper and lower coils 2a, 2b via the slit 3a to constitute the water-cooled metal crucible 1. The bottom of the water-cooled metal crucible 1 is a bottom hole having the same diameter as the body. A metal material is placed inside the water-cooled metal crucible 1 and melted in the water-cooled metal crucible 1 to form a molten metal 4. The segment 3 constituting the water-cooled metal crucible 1 is cooled so as not to be heated by water or the like.
[0026]
The bottom of the water-cooled metal crucible 1 is directly connected to a mold 10 made of water-cooling and having a slit in the upper part, and a drawing casting apparatus 15 is provided in the lower part. The bottom hole of the water-cooled metal crucible 1 is fitted in the bottom hole and has a water-cooling function at the bottom, a pull-out plug 11 that drives the plug 12, and a pull-out drive unit lifting platform 14. Is directly connected to the pulling drive device 13.
[0027]
In FIG. 5, since the molten metal 4 is controlled to be solidified in the mold 10 at the time of drawing driving, the power supply power, the drawing speed, the drawing driving stopper 11 and the cooling of the water-cooled mold 10 are controlled. When both the water-cooled metal crucible 1 and the mold 10 are made of metal, in order to avoid damage due to short circuit or discharge between the two during operation, a structure having a minute space to be electrically insulated or water-cooled is used. It is desirable that a thin insulator be inserted into the contact surface between the metal crucible 1 and the mold 10.
[0028]
When the metal material is melted, the pull-out driving plug 11 is fitted in the bottom hole of the water-cooled metal crucible 1. When the molten metal 4 in the vicinity of the crucible bottom hole and the distal end portion of the extraction driving plug 11 are formed in a semi-molten state during the extraction driving, the material plug 12 of the same material as the molten metal 4 is used at the distal end of the extraction driving plug 11. In this case, the material plug 12 is not cooled by water, but is cooled by contact heat transfer from the pull-out driving plug 11 cooled at the lower part. At the time of extraction driving, the position of the mold 10 is fixed, and the extraction driving device 13 is driven to drive the extraction driving plug 11 and the material plug 12. In this case, there are various methods for pulling drive, such as pulling down after driving upward at the start of drawing, and continuous pulling operation, intermittent pulling operation, reversible operation in the vertical direction, etc. Though possible, the molten metal 4 is continuously solidified in the mold 10 and drawn. The molten metal 4 in the mold 10 receives heat from the mold 10 at the time of melting, but its volume shrinks due to solidification, so that it can be pulled out without contacting the mold 10, but the inner diameter of the mold 10 is expanded in a tapered shape at the bottom. Use different things according to usage conditions.
[0029]
When pulling drive is performed, the material stopper is not used and the upper part of the pulling drive plug 11 is in a soft contact state, and after the pulling drive, the solidified layer on the top of the plug is redissolved and cast into hot water. Use copper stoppers. In this case, a resolidified layer is formed in the vicinity of the bottom hole of the crucible by removing heat to the extraction drive plug, but the resolidification layer is eliminated by the removal of heat removal by lowering the extraction drive plug 11 and the penetration of magnetic flux into the bottom. As an eddy current flows through the re-solidified layer, the re-solidified layer can be dissolved and discharged. In this case, casting is performed by one shot, but there is an advantage that the hot water stroke is shorter than the conventional one.
[0030]
The mold 10 is preferably made of water-cooled metal in order to prevent impurities from being mixed into the metal solidified by the molten metal 4. In order to control at the time of casting, a coil (not shown) can be wound around the mold 10, and the mold 10 has a structure with a slit below the position where the coil is wound, It can be set as the structure which controls the temperature control at the time of solidification, the contact to a casting_mold | template, etc.
[0031]
6 and 7 are configuration diagrams of an example in which the cold crucible melting and casting apparatus of the invention of FIG. 5 can be performed under atmosphere control, FIG. 6 is a state diagram before casting, and FIG. 7 is a state diagram during casting. . 6 and 7 are different from FIG. 5 in that, instead of FIG. 5 being melting casting in the atmosphere, the water-cooled metal crucible 1 and the upper and lower coils 2a and 2b, the mold 10, both the material plug 12, the extraction drive plug 11. The pultrusion casting apparatus 15 is housed in a vacuum chamber 16 equipped with a vacuum pump and an atmosphere control device, and the movable part of the pultrusion casting apparatus 15 can be expanded and contracted between the pultrusion drive unit lifting platform and the vacuum chamber 16. It is the point which connected with the bellows 17 etc. which can be expanded and extended so that a vacuum state could be maintained.
[0032]
By comprising in this way, melt | dissolution casting in a vacuum or inert gas atmosphere is attained, and deoxidation from a melt | dissolution material and the metal oxidation prevention at the time of melt | dissolution casting can be performed.
[0033]
【The invention's effect】
According to the present invention, the coil wound around the outer periphery of the water-cooled crucible has two or more coils having different frequencies, and the coil on the upper side of the water-cooled crucible is in contact with the crucible by adopting a low frequency with excellent electromagnetic force characteristics. The amount of heat removed from the crucible can be reduced by reducing the area, and the coil at the bottom of the water-cooled crucible uses a higher frequency than the upper coil, which excels in heating characteristics, to actively heat the molten metal and Coagulation can be suppressed. In addition, since the upper and lower coils can be controlled independently, melting of refractory metals and alloys that were difficult with conventional cold crucible melting and casting equipment, as well as melting with cast metals and metals that can be melted with conventional equipment. Even when the amount is increased as compared with the prior art, it is possible to cope with melting and casting.
[Brief description of the drawings]
FIG. 1 is a block diagram of a main part of an embodiment of the present invention. FIG. 2 (a) is a cross-sectional view of a water-cooled metal crucible simulating a balance state between an electromagnetic repulsive force acting on a molten metal and a molten metal's static pressure. FIG. 4B shows the height (depth) from the molten metal surface to the bottom on the horizontal axis, the molten metal height dh, and the electromagnetic repulsive forces F2 and F3 acting on the molten metal at each position of the dh in the vertical axis direction. FIG. 3 is a block diagram of the main part of the embodiment of the invention of claim 1. FIG. 4 is a block diagram of the main part of the embodiment of the invention of claim 2. FIG. FIG. 6 is a configuration diagram of an example in which the cold crucible melting and casting apparatus of the invention of FIG. 5 can be performed under atmosphere control, and is a state diagram before casting. FIG. 8 is a structural diagram of a conventional example. FIG. 9A is an electromagnetic repulsive force acting on a molten metal and a molten metal in the structure of FIG. FIG. 8B is a cross-sectional view of a water-cooled metal crucible simulating the balance state between the molten metal height dh with the horizontal axis representing the height (depth) from the molten metal surface to the bottom in the configuration of FIG. dh A diagram showing the electromagnetic repulsive force F1 acting on the molten metal at each position in the vertical axis direction
DESCRIPTION OF SYMBOLS 1 Water-cooled metal crucible 2a Upper coil 2b Lower coil 5, 6 High frequency power supply 7, 8, 10 Mold 9 Suction device 11 Pull-out drive plug 12 Material plug 15 Pull-out casting device 16 Vacuum chamber 17 Bellows

Claims

Two or more segments electrically insulated inside a circular coil are arranged in the circumferential direction of the coil to form a water-cooled metal crucible, the coil is excited using a high frequency power source, and the metal material in the water-cooled metal crucible A cold crucible melting device that forms a skull between the molten metal in which the metal material is melted and the water-cooled metal crucible, and the metal melted in the water-cooled metal crucible is inclined to the water-cooled metal crucible. In a cold crucible melting and casting apparatus that casts on a mold installed at the lower part of the water-cooled metal crucible by rolling, the coil is provided in two stages above and below the outer periphery of the water-cooled metal crucible, and the current that is passed through the upper coil when the metal material is melted by the frequency of lower than the frequency of the current supplied to the lower coil, the melt bottom Ru said through the skull URN in contact with, the cold crucible melting and casting apparatus wherein molten metal upper is characterized in that to avoid contact with the crucible.

Two or more segments electrically insulated inside a circular coil are arranged in the circumferential direction of the coil to form a water-cooled metal crucible, the coil is excited using a high frequency power source, and the metal material in the water-cooled metal crucible A cold crucible melting device that forms a skull between the molten metal in which the metal material is melted and the water-cooled metal crucible, wherein the metal melted in the water-cooled metal crucible is sucked into the water-cooled metal crucible In a cold crucible melting and casting apparatus for casting on a mold provided at the lower or upper part, the coil is provided in two stages above and below the outer periphery of the water-cooled metal crucible, and the frequency of the current applied to the upper coil when the metal material is melted is reduced. by lower than the frequency of the current supplied to the coil, the melt bottom in contact with the crucible through the skull Cold crucible melting and casting apparatus wherein molten metal top, characterized in that to avoid contact with the crucible.

Two or more segments electrically insulated inside a circular coil are arranged in the circumferential direction of the coil to form a water-cooled metal crucible, the coil is excited using a high frequency power source, and the metal material in the water-cooled metal crucible A cold crucible melting device that forms a skull between the molten metal in which the metal material is melted and the water-cooled metal crucible, wherein the metal melted in the water-cooled metal crucible is formed in the water-cooled metal crucible. In a cold crucible melting and casting apparatus for casting in a water-cooled mold directly connected to the bottom, the coil is provided in two stages above and below the outer periphery of the water-cooled metal crucible, and the frequency of the current applied to the upper coil when the metal material is melted is set. by lower than the frequency of the current supplied to the lower coil, the melt bottom in contact with the crucible through the skull, the soluble Cold crucible melting and casting device top, characterized in that to avoid contact with the crucible.

4. The cold crucible melting and casting apparatus according to claim 3, wherein a pulling drive plug is provided at the bottom of the water-cooled metal crucible to prevent the molten metal from falling, and casting is performed by pulling out the plug. Casting equipment.

5. The cold-crucible melting and casting apparatus according to claim 4, wherein the pull-out driving plug has a water-cooling function, and the tip portion is made of a water-cooled metal that can be removed and replaced.

6. The cold crucible melting and casting apparatus according to claim 4 or 5, wherein the pulling drive plug is detachably attached to the upper part of the pulling drive plug and made of the same kind of metal as the melted metal. A cold crucible melting and casting apparatus comprising a material plug.